Background Cylindroma of the breast is a rare benign neoplasm. Since its first description in 2001, 20 cases have been reported in the literature. Methods and results We report another case of this rare tumor in a 60-year-old woman with demonstration of the underlying molecular alteration. Histologically, the tumor showed the typical “jigsaw” pattern of a dual population of cells with a triple-negative phenotype. The pathognom...